Short-range optical interconnection is a very promising solution for implementing a large-capacity switching between large-scale parallel multiprocessor chips in the future. A transmission capacity may be expanded by introducing a wavelength division multiplexing (WDM) technology, a polarization division multiplexing (PDM) technology, and a mode division multiplexing (MDM) technology, and the WDM and PDM technologies have been applied to a single-mode optical waveguide.
A multimode waveguide may greatly expand the transmission capacity by using the mode division multiplexing technology. Currently, in the prior art, there is a solution for implementing a mode multiplexer and a mode demultiplexer that are used to perform a direct mode conversion between a multimode waveguide and a single-mode waveguide in a system on chip. The mode multiplexer and the mode demultiplexer may implement the short-range optical interconnection by using the multimode waveguide.
In the system on chip, during establishment of an optical switching system of the multimode waveguide, in addition to the direct mode conversion between the multimode waveguide and the single-mode waveguide, switching between signals in different modes needs to be implemented, so as to meet requirements for switching and transmission between multiple modes in the optical switching system. In the prior art, as shown in FIG. 1, a multimode demultiplexer is used to demultiplex an input multimode signal into a single-mode waveguide, and then a multimode multiplexer is used to multiplex the signal into a multimode waveguide, so as to complete a conversion between different modes.
However, in the prior art, to implement a conversion between different modes, because two conversion devices, that is, a multimode demultiplexer and a multimode multiplexer, are used, an insertion loss (the insertion loss refers to a signal loss caused when a cable or a component is inserted between a transmitter and a receiver) is relatively large. In addition, in the prior art, all modes are converted in a unified manner, and when only some modes need to be converted, all the modes may need to be demultiplexed into a single-mode waveguide, and therefore, an overall size is relatively large, and an optical switching system cannot be easily implemented.